Low tension lead

MG: MGA (1955-62) • MGB (1962 to september 1974) • MGC (1967-69)

Land Rover: Late Series IIA and early Series III 4 cylinder Petrol to engine suffix 'C' (1964-77)

Jaguar: XK150 (1957-61) • Mk9 (1958-61) • XJ6 Series I and II with Lucas 22D6 distributor

Austin Healey: BJ8 (1963-68)

Mini: with Lucas 25D4 distributor

Triumph: TR3, TR3A, TR4 and TR4A with Lucas 25D4 distributor • TR5/250 and TR6 (1967-76) • Herald (1959-71)

Sprite / Midget: 948, 1098 and 1275 cc with Lucas 25D4 distributor

Morris: Minor with 1098 cc engines (1962-71)

Alvis: TD 21, TE 21 and TF 21 (1958-67)

for Lucas distributors. Variant with lucar terminal.
Please note: downward pointing connector

The low tension lead is subject to a lot of vibration. It is not all that unusual for the copper strands to break within the insulation at the connector. To the eye everything looks OK. The ignition circuit can intermittently cut in and out creating frustration and even some danger. If your engine starts cutting out and in or just stops then is OK after you check connections, a broken low tension lead should be among the suspects.
It is a good idea to carry a spare in your field repair kit.